Overview

Current particulate matter regulations control the mass concentration of particles in the atmosphere regardless of composition, but some primary and/or secondary particulate matter components are no doubt more or less toxic than others. Testing direct emissions of pollutants from different sources neglects atmospheric transformations that may increase or decrease their toxicity. This work describes a system that conditionally samples particles from the atmosphere depending on the sources or source combinations that predominate at the sampling site at a given time. A single particle mass spectrometer (RSMS-II), operating in the 70-150 nm particle diameter range, continuously provides the chemical composition of individual particles. The mass spectra indicate which sources are currently affecting the site. Ten ChemVol® samplers are each assigned one source or source combination, and the RSMS-II controls which one operates depending on the sources or source combinations observed. By running this system for weeks at a time, sufficient sample is collected by the ChemVols for comparative toxicological studies. This presentation describes the instrument and algorithmic design, implementation, and first results from operating this system in Fresno, California, during summer 2008 and winter 2009.

Speaker Biography

Anthony Wexler, Ph.D., is Professor of Mechanical and Aerospace Engineering, Civil and Environmental Engineering, and Land, Air and Water Resources. Dr. Wexler is also Director of the Air Quality Research Center (AQRC), Crocker Nuclear Laboratory (CNL), and USEPA's San Joaquin Valley Aerosol Health Effects Research Center (SAHERC).